adding a key name to an array in javascript

Question

I have an array of objects and I am using the map function to reduce that array of objects to be an array of a single element in each object. After that I am removing the dup elements in that array. After doing that I have a array like arr = ["100", "101", "103", "104", "105"] but I want to have a key name for each element like arr =[{id: 100},{id: 101}, {id: 103},{id: 104},{id: 105}].

My initial array of objects:

const options = [
       { id: 1, value: 'chocolate', label: 'Chocolate' },
       { id: 2,value: 'strawberry', label: 'Strawberry' },
       { id: 3,value: 'vanilla', label: 'Vanilla' },
       { id: 4,value: 'vanilla', label: 'Vanilla' },
];

let testArr = options.map(a => a.value);
let uniqueTest = [...new Set(test)];

So uniqueTest gives an array like ["chocolate", "strawberry", "vanilla"]

What I want is an array with key names if that is possible.

Welcome to Stack Overflow! Please read through the help center, in particular How do I ask a good question? Your best bet here is to do your research, search for related topics on SO, and give it a go. If you get stuck and can't get unstuck after doing more research and searching, post a minimal reproducible example of your attempt and say specifically where you're stuck. People will be glad to help. — T.J. Crowder
– T.J. Crowder, Commented Jul 21, 2020 at 17:24
Take a look at Array.prototype.map! You can then map each key to an object { id: key }. — CherryDT
– CherryDT, Commented Jul 21, 2020 at 17:24

Beginner · Accepted Answer · 2020-07-21 17:28:50Z

3

To get the desired result, you can use Array.map, Which will give you a new array copy. And for changing from string to number you can use Number function Which will convert the string to a number.

Kindly check the below snippet

let arr = ["100", "101", "103", "104", "105"]
let output = arr.map(item => ({id: Number(item)}))
console.log(output)

answered Jul 21, 2020 at 17:28

Beginner

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2 Comments

Shalin Patel Over a year ago

I was attempting that but I was missing the parenthesis around the curly brackets. Thanks it solved my question.

Beginner Over a year ago

@ShalinPatel happy to help, kindly accept if it worked for you. So it will be helpful for others on future references :)

Siva Kondapi Venkata · Accepted Answer · 2020-07-21 17:38:01Z

1

Use map and make sure map method is returning with desired key name.

const options = [
       { id: 1, value: 'chocolate', label: 'Chocolate' },
       { id: 2,value: 'strawberry', label: 'Strawberry' },
       { id: 3,value: 'vanilla', label: 'Vanilla' },
       { id: 4,value: 'vanilla', label: 'Vanilla' },
];
let testArr = options.map(a => a.value);
let uniqueTest = [...new Set(testArr)];


const output = uniqueTest.map(key => ({key}));
console.log(output)

answered Jul 21, 2020 at 17:38

Siva Kondapi Venkata

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Comments

BARNOWL · Accepted Answer · 2020-07-21 17:40:39Z

You can try using reduce as its not only used for getting the single desired output, it could be used to transform arrays into object key pairs.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce

arr = ["100", "101", "103", "104", "105"]

const newArr = (acc, cv) => {
   return {...acc, ["id"]: cv};
}

const findById = arr.reduce(newArr, {});

console.log(findById)

Another example

const options = [{
    id: 1,
    value: 'chocolate',
    label: 'Chocolate'
  },
  {
    id: 2,
    value: 'strawberry',
    label: 'Strawberry'
  },
  {
    id: 3,
    value: 'vanilla',
    label: 'Vanilla'
  },
  {
    id: 4,
    value: 'vanilla',
    label: 'Vanilla'
  },
];
const newArr = (acc, cv) => {
  return { ...acc,
    [cv.label]: cv
  };
}

const findByLabel = options.reduce(newArr, {});

console.log(findByLabel)

https://jsbin.com/lixekodevi/edit?js,console

Cody Gray · Accepted Answer · 2020-07-22 05:27:28Z

1

Here is what you want :

const options = [
       { id: 1, value: 'chocolate', label: 'Chocolate' },
       { id: 2,value: 'strawberry', label: 'Strawberry' },
       { id: 3,value: 'vanilla', label: 'Vanilla' },
       { id: 4,value: 'vanilla', label: 'Vanilla' },
];

let testArr = options.map(a => a.value);
let uniqueTest = Array.from(new Set(testArr),value=>({value}));
console.log(uniqueTest)

edited Jul 22, 2020 at 5:27

Cody Gray♦

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answered Jul 21, 2020 at 17:50

8HoLoN

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